Charles mortimer lindsey



UNITED STATEs PATENT OFFICE.

CHARLES MORTIMER LINDSEY, OF PITTSBURG, PENNSYLVANIA, ASSIG NOR TO THE PITTSBURG CRUSHED STEEL COMPANY, LIMITED, OF SAME PLACE.

cu'r'rme, GRINDING, AND POLISHING MATERIAL.

SPECIFICATION forming part of Letters Patent No. 466,277, dated December 29, 1891.

Application filed April 16,1891. Serial No. 389,068. (lilo specimens.)

.To all whom it may concern:

Be it known that I, CHARLES MORTIMER LINDSEY, of Pittsburg, in the county of Allegheny and State of Pennsylvania, have 'inventeda new and useful Improvement in Cutting, Grinding, and Polishing Material, of which the following is a full, clear, and exact description.

My invention consists in an improved article of manufacture for the grinding, cutting, or polishing of stone, metal, and other hard substances; and it consists in small particles formed by fracture or crushing of hardened steel, such particles being subsequently tempered to impart to them greater toughness and durability. Such substance possesses many advantages. It is hard, very durable,

. and performs the work of cutting, grinding,

and polishing very rapidly. The'particles may be of various sizes, varying from a powder to grains of a size adapted to pass through a No. 10 sieve. Its manner of use is similar to that practiced with other substances of a like nature. For example, the fine powder is used as emery-powder is commonly used, and the grains maybe used with grinding-wheels, saws, or otherwise.

-I shall now describethe mode of man ufacture of this substance which I prefer to employ, premising, however, that the invention is'not limited to any particular process of hardening the steel nor to crushing or fracto ring machinery of any one pattern.

I take pieces of steel-good crucible steel is the best for the purposeand harden them, preferablybyheatim them to a temperature of about 2,500 Fahrenheit, suflicient to burn the steel, and quench it by plunging it in cold water or in a tempering solution, a suitable mixture for the purpose being a solution of two quarts of common salt and one pound of soda in a gallon of water. Such burning and hardening make the steel very hard and brittle, giving it a crystalline granular structure. I then place the steel under a hammer or crushing-machine and subject it to repeated blows until it isreduced to smallparticles, which may be of various sizes, from the form of a fine powder to that of grains such as above mentioned. The steel particles are thentempered in any-suitable way,but preferably by the following mode: They are placed in a pan or in a receptacle of any other suitable form and are there heated to a temperature of about 460 Fahrenheit, until the particles change in appearance 'to a straw color, and they are t-hen'cooled by subjecting them to cold air, preferably forced upon the particles'by means of a. blast-fan or pump. This tempering changes not only the appearance of the particles, giving them a dull metallic luster, but also greatly improves their character, rendering them tougher and much more able than before to resist the crumbling and reducing action of grinding and cutting. The particles, either before or after the tempering, may be separated into lots of diiferent sizes by passing them through proper sieves. After tempering the material is ready for use.

' I claim As a new article of manufacture, a cutting, grinding, or polishing material composed of tempered particles of fractured steel which has been crystallized byheatingto a burnt temperature and quenching, substantially as and for the purposes deseribed. I

In testimony whereof I have hereunto set my handthis 11th day April, A. D.'189l.

CHARLES MORTIMER. LINDSEY. Witnesses:

Enw. A. HEss, M. M. KANN. 

